CATV services have historically delivered audio and video signals within a forward direction environment. That is, signals have been transmitted from the CATV operations center to the subscriber exclusively. However, now that CATV operators are allowed to offer services like internet access, telephony, and other interactive services to subscribers, it is necessary to have transmissions flow in the reverse direction for two way communication between the subscriber and the CATV operations center. This reverse direction is commonly called the "return path".
Most CATV operators have elected to use a 5 to 40 MHz frequency range for the reverse transmissions. Since the return path of 75-ohm coaxial cable systems has largely been ignored up to the present date, signal level inequalities within the cable system architecture creates integrity problems within a given return path spectrum. Thus, a means to balance signal levels is required in order to improve the transmission integrity of return path signals.
An article entitled "Designing the Return System for Full Digital Services", written by Dean A. Stoneback and William F. Beck discusses problems associated with signal level inequality in return path transmissions, and proposes methods for designing and setting up a return path system. This article is expressly incorporated by reference. However, there remains a need for simple circuitry which balances signal levels within a given return path spectrum, while also filtering signals below the return path spectrum to prevent noise related harmonics from disrupting signals within the return path spectrum.